This invention is directed to an electro-chromic display driving circuit, and in particular to driving an electro-chromic display by effecting a transient characterized by an initial sharp increase in current and a subsequent slower decrease in current across the respective conductor electrodes of the electro-chromic display.
Heretofore, electro-chromic display driving circuits have been formed of MOS transistors in order to take advantage of the reduced power consumption which such MOS transistors provide. Nevertheless, the reduced power consumption characteristic of MOS transistors limits their effectiveness in obtaining sufficient contrast when utilized with electro-chromic display cells. Specifically, MOS transistors have a limited current capacity, and are designed to substantially suppress the transient currents, which render the level of coloring of the electro-chromic display cells less than completely satisfactory. Moreover, in order to obtain a better level of coloring of the electro-chromic display cells, when utilizing MOS transistors it is necessary to elevate the operating voltage applied to the respective display cells. Accordingly, the criteria for obtaining an improved electro-chromic digital display are not met by the use of MOS transistors.